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R51/3 - engine won't start after carbs cleaning

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Micha
Posts: 693
Joined: Fri Oct 12, 2007 2:24 am
Location: Israel

R51/3 - engine won't start after carbs cleaning

Post by Micha »

While I wait for the new fuel tank to arrive in mid-January (there's a post here regarding this issue), I have once again finished patching the old one with tin solder, and there seems to be no leakage in so far.
So I went and assembled it and tried to get the engine run.
What I get is right side run after lots and lots of kicking and then it dies (exhaust gets extremally hot there, while only warm on the left). Seems that left is not working, though exhaust gets a bit warm there.
Further start attempts as part of the morning gymnastics are answered with a heavy backfire on the right. Can no longer start the engine. Took the spark plugs out: they where wet. Dried and ventilated the cylinders. Still no success.
When the engine was working, opening the throttle beyond the low-medium rpm responded with choking engine.

Carbs where cleaned.
They get fuel.
Stop screws on carbs where rotated in 2 turns after touching the sliders.
Pilot screws where tightened slightly and turned back 2 turns.
There are sparks from the new PowerDynamo system and valve clearance was checked 3 times.

Any ideas? My leg hurts.

EDIT:
After further thought, could it be that the needle is not at the right height?
I attach pictures. How can I know the required height? The carbs were purchased as new at Mark Huggett, and are 24mm type (the originals were shot).
Attachments
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Michael Steinmann
R51/3 1952
Engine Nr. 529466

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bmwsog
Posts: 105
Joined: Wed Mar 19, 2014 2:53 pm

Re: R51/3 - engine won't start after carbs cleaning

Post by bmwsog »

I have a 1951 R 51/3.

Don't forget timing and mag/It all works together
and the devil is in the details. Keep alternating plugs as they get wet-then dry.Then new plug.
That was an old tip from Vech.


Ridge Marriott
LTC R Marriott--Current-1951 R-51/3
1962 R 69 S 1975 SS R-90 S
Past:1974 SS R 90 S, 74 R 90 , 77 R 100S, 1960 R 50/2,1973 R 75/5, 1977 R 75/7, 1977 R 100 , 1972 R 75 /5

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Micha
Posts: 693
Joined: Fri Oct 12, 2007 2:24 am
Location: Israel

Re: R51/3 - engine won't start after carbs cleaning

Post by Micha »

Thanks Ridge,
Plugs are the 2nd new set installed.
Ignition & charging are new P-D system.
Michael Steinmann
R51/3 1952
Engine Nr. 529466

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Micha
Posts: 693
Joined: Fri Oct 12, 2007 2:24 am
Location: Israel

Re: R51/3 - engine won't start after carbs cleaning

Post by Micha »

I have a feeling the right side is working with a too poor mixture and that's why it's getting so hot.
Does this theory make sense?
Does screwing the pilot screw in - enrich the mixture? Or rather screwing it out?

Looking further at the carbs pictures, I think I'm in the second hole in terms of needle height.

And what does the back fire I got on the right hint suggest?

EDIT:
Plugs are Salis NGK's items and are put in as-is.
Maybe I should play around with the gaps?
I think that they are a direct plug & play, but can be wrong here?
Last edited by Micha on Tue Dec 21, 2021 10:46 am, edited 1 time in total.
Michael Steinmann
R51/3 1952
Engine Nr. 529466

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schrader7032
Posts: 8467
Joined: Fri Oct 27, 2006 3:00 am
Location: San Antonio, TX

Re: R51/3 - engine won't start after carbs cleaning

Post by schrader7032 »

Those carbs should have air screws to control the mixture. Going in cuts off air making it richer.

Have gone thru any synching steps?
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

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Micha
Posts: 693
Joined: Fri Oct 12, 2007 2:24 am
Location: Israel

Re: R51/3 - engine won't start after carbs cleaning

Post by Micha »

I am trying according to this site: https://w6rec.com/adjusting-the-2-bing-carbs/
I forgot to mention that both accelerator & carb cables are also new Salis products.

EDIT:
By the way, I think I read in the assembly instructions of the new P-D ignition/charging system, that I must not operate the method of disconnecting the ignition cable on one side and vice versa, in order to set one side separately. It states - never pull a plug wire while motor running.
Michael Steinmann
R51/3 1952
Engine Nr. 529466

Werner1111
Posts: 97
Joined: Fri Dec 16, 2016 6:39 pm
Location: Hollyweird, CA

Re: R51/3 - engine won't start after carbs cleaning

Post by Werner1111 »

Hi Michael - is the new P&D Charging and Ignition system new, as in brand new? Did the motorcycle ever run with it installed? It sounds like an ignition problem to me. This comes after just getting an R69 running and having dealt with the magneto, coil and then differential timing issues.
R69 R90/6 R100/7 R100S R1150GSA S2R1000

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Micha
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Joined: Fri Oct 12, 2007 2:24 am
Location: Israel

Re: R51/3 - engine won't start after carbs cleaning

Post by Micha »

Well it is brand new, but the motor run with it until I faced the leaking gas tank issue.
Then I parked the bike so I could take care of the gas tank first.
I don't think it is the problem.
Michael Steinmann
R51/3 1952
Engine Nr. 529466

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schrader7032
Posts: 8467
Joined: Fri Oct 27, 2006 3:00 am
Location: San Antonio, TX

Re: R51/3 - engine won't start after carbs cleaning

Post by schrader7032 »

I would certainly agree that you should not pull a spark plug cap away from the plug while the engine is running. That could result in a backwave through the system which can damage the sensitive electronics. In the old days, pulling the plug resulted in the spark energy flowing through the safety gap that was built into the magneto ignition.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

FL54
Posts: 188
Joined: Sun Aug 12, 2018 5:09 pm
Location: Central Oregon

Re: R51/3 - engine won't start after carbs cleaning

Post by FL54 »

I’m certainly no expert but I would caution against going off in multiple directions looking for a fix. In my experience, it usually ends up being the last thing that was worked on.
Central Oregon

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